1892.] 



by Friction in the Sores of Rifled Guns. 



417 



The results of this series confirm generally those of the previous 

 series. The loss of energy due to the friction of the uniform rifling 

 amounts to 14 ft. -tons, or, a little more than 1 per cent., while that 

 due to friction and other causes with the parabolic rifling amounts to 

 57 ft.-tons or about 4'1 per cent., and nearly the same as before. 

 The difference between the uniform and parabolic rifling should have 

 been less than in the former series ; as a matter of fact it is greater, 

 but this may be accounted for by variations in the powder as pre- 

 viously suggested, as the suppression of a single round in each of the 

 two guns would make the results in accordance with theory. 



The coefficient of friction calculated from the uniform rifling gives 

 & = 0-133. 



The driving ring in this series was amply sufficient for rotative 

 purposes, there not being even with the highest velocity obtained the 

 slightest appearance of slip or undue wear. 



In the fourth series the driving ring was of the Government pattern, 

 but longer, and as is shown in section " C," and the results obtained 

 were as given in the table. 



Table V. Results of Experiments with Driving Rings of 

 Section " C." 



The loss of velocity due to the uniform and parabolic rifling is, 

 from these experiments, respectively 33 and 52 ft.-secs., and the loss 



